/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.flink.runtime.checkpoint;

import javax.annotation.Nullable;

import java.io.Serializable;

import static org.apache.flink.util.Preconditions.checkNotNull;

/**
 * A snapshot of the checkpoint stats.
 */
public class CheckpointStatsSnapshot implements Serializable {

	private static final long serialVersionUID = 8914278419087217964L;

	/** Snapshot of the checkpoint counts. */
	private final CheckpointStatsCounts counts;

	/** Snapshot of the completed checkpoints summary stats. */
	private final CompletedCheckpointStatsSummary summary;

	/** Snapshot of the checkpoint history. */
	private final CheckpointStatsHistory history;

	/** The latest restored checkpoint operation. */
	@Nullable
	private final RestoredCheckpointStats latestRestoredCheckpoint;

	/**
	 * Creates a stats snapshot.
	 *
	 * @param counts Snapshot of the checkpoint counts.
	 * @param summary Snapshot of the completed checkpoints summary stats.
	 * @param history Snapshot of the checkpoint history.
	 * @param latestRestoredCheckpoint The latest restored checkpoint operation.
	 */
	CheckpointStatsSnapshot(
			CheckpointStatsCounts counts,
			CompletedCheckpointStatsSummary summary,
			CheckpointStatsHistory history,
			@Nullable RestoredCheckpointStats latestRestoredCheckpoint) {

		this.counts = checkNotNull(counts);
		this.summary = checkNotNull(summary);
		this.history = checkNotNull(history);
		this.latestRestoredCheckpoint = latestRestoredCheckpoint;
	}

	/**
	 * Returns the snapshotted checkpoint counts.
	 *
	 * @return Snapshotted checkpoint counts.
	 */
	public CheckpointStatsCounts getCounts() {
		return counts;
	}

	/**
	 * Returns the snapshotted completed checkpoint summary stats.
	 *
	 * @return Snapshotted completed checkpoint summary stats.
	 */
	public CompletedCheckpointStatsSummary getSummaryStats() {
		return summary;
	}

	/**
	 * Returns the snapshotted checkpoint history.
	 *
	 * @return Snapshotted checkpoint history.
	 */
	public CheckpointStatsHistory getHistory() {
		return history;
	}

	/**
	 * Returns the latest restored checkpoint.
	 *
	 * @return Latest restored checkpoint or <code>null</code>.
	 */
	@Nullable
	public RestoredCheckpointStats getLatestRestoredCheckpoint() {
		return latestRestoredCheckpoint;
	}
}
